In terms of skills yes.
But experience is important as well and leadership.
He lacks those.
But potential is there and we are lucky to have him.
Against Everton, you don't play world-class attackers and Ruben's experience and leadership is more important.
Against Arsenal, under Rodri-Bernardo's leadership, Khusanov played great match and we would have probably struggled with Ruben there, as we played high pressing and needed pace to survive their counters.
But against Everton, when Rodri wasn't there and things went wrong, Khusanov started to make simple mistakes.
Same applies to Guehi, who has just arrived to a big club from low-tier team.
That's why Ruben-Gvardiol duo is important for marathon, as most games we play against average teams and we just need to avoid simple mistakes, for which their experience helps us a lot.
if we order our defenders considering skills + experience.
1) Gvardiol - great skills, good experience
2) Ruben - average skills, great experience
3) Khusanov - great skills, small experience
4) Guehi - good skills, good experience